Your car may already be using your phone's data. If you pair your phone with your car there is a Bluetooth protocol that lets your car's cellular radio authenti

Your car may already be using your phone's data. If you pair your phone with your car there is a Bluetooth protocol that lets your car's cellular radio authenticate using your phone's SIM. But, yes, if they try sending absurd amounts of data people are going to notice their allowances running out.